XX11 



INTEODUCTION. 



again, what is the Eock Wren (Xenicus gilviventris) but an extreme development of the Bush 

 Wren {Xenicus longipes) — which has put off its green plumage for the dun-coloured dress 

 more in harmony with its surroundings among the rocks on the open mountain, and has 

 acquired a longer hind claw, so as to fit it for this different habitat — or vice versa? The 

 particular direction of the development does not of course affect the argument. And it is a 

 significant circumstance that I possess intermediate forms ; so much so, in fact, that I have 

 been in doubt as to which of the two species they really belonged. Or, to to take just one more 

 case : who can doubt that the fleshy membrane on the bill of our blue Mountain Duck 

 (Hymenolcemus malacorhynchus) has been specially developed to enable it to hunt the more 

 successfully for the peculiar stone-encased caddis-worm of our mountain streams, which now 

 forms its principal article of food ? 



But now to revert to my main line of argument. In considering the problem of representative 

 species in the North and South Islands respectively, it must be borne in mind that there are 

 probably many broken links in the chain of succession through the disappearance of representative 

 forms. We all know that the existing avifauna is being stamped out and destroyed by a variety 

 of artificial causes, not the least among them being the naturalisation of foreign birds by way of 

 acclimatisation, on the one hand, and the introduction of bloodthirsty animals like stoats, 

 weasels, and ferrets, on the other. But long before the effects of our drastic colonisation made 

 themselves felt, many of the ground species were dying out, in obedience, no doubt, to that in- 

 scrutable law of nature whereby races of animals and plants, apparently of their own accord, die 

 out and give place to other forms of life. I remember, when I was a boy, the interest with which 

 I followed the Maoris' descriptions of birds that had even then become rare or were disappearing 

 from the land. One bird, a species of Eail or Coot apparently, was often mentioned to me under 

 the name of Pukunui — so called from the abnormal size of its stomach. It was described as a 

 reddish bird, frequenting swamps and marshes, and I was constanly hearing of it. Indeed, I never 

 made an excursion among the Maoris anywhere, without making diligent inquiry for the Pukunui. 

 I offered liberal rewards, and often felt that the bird was almost within my grasp. At length, 

 at the small bush settlement of Mareikura, on the North Wairoa Eiver, one was caught at the 

 edge of a raupo swamp near the village by my trusty lieutenant, Tamati Nui. It had been taken 

 unhurt, and, pending an opportunity of forwarding it to me, it was kept tethered by a flax-string 

 in the " marae " or open courtyard. A passing Maori unconsciously snapped the string with his 

 foot, and, unfortunately for me and for science, this " rara avis in terris " made its escape. 

 Nearly fifty years have elapsed since this occurence, and I have never so much as heard of the 

 capture of another Pukunui ! 



Owing to its fore-neck and breast being represented as ferruginous red, I am inclined to think 

 that Colenso's Coot, described on page 75, was in reality this bird. 



In this connection, and also as marking the tendency towards extinction in certain lines, it 

 is of interest to notice that the Ealline genus Notomis was contemporary with the smaller species 

 of Moa, and that the bones of the living bird obtained in Otago differ so much from those of the 

 fossil remains discovered by Mr. Walter Mantell at Waingongoro, in the North Island, and 

 referred by Professor Owen to a form which he named Notomis mantelli, in honour of the 

 discoverer, that Dr. A. B. Meyer, of Dresden, has proposed to discriminate two species, dis- 

 tinguishing the southern form as Notomis hochstetteri, in compliment to the Austrian explorer. 

 If Dr. Meyer should be right in his determination, we have here a beautiful instance of repre- 

 sentation, the North Island species having long since disappeared, whilst the South Island species 

 is verging on extinction. 



I think I have now noticed all the main points bearing on this question arising out of a 

 study of the birds of the North and South Islands. But it is to the smaller insular areas that we 



